As I've seen this asked in about a dozen threads over the last week, I thought I'd clear this up.

Any harddrive made in at least the last 5 years can be mounted at any angle.

Upside down, on their side, on one end, at 45 degrees, balanced on one corner, whatever you like. You can even change the orientation without reformatting.

All that's important is that you avoid moving the hard drive while it's in motion, and you mount it in a secure fashion, so it won't fall or get banged against the side of the case while in operation. Also, make sure it's mounted in such a way that it won't over heat. Checking the SMART temperatures for a few days after mounting it with a program such as Speedfan is a good practice.

I do know for a fact this is true, as I've had harddrives operating in any angle imaginable for months on end, and it's just common sense. The heads of the HD operate under extreme accelerations, many tens of Gs. One extra G in any direction will be completely unnoticed. Heads aren't programmed with the physical locations of tracks and sectors, they find them intelligently.

6.7.4 Drive mountingThe drive will operate in all axes (6 directions). Performance and error rate will stay within specification limits if the drive is operated in the other orientations from which it was formatted.

Western Digital wrote:

Physical mounting of the drive:WD drives will function normally whether they are mounted sideways or upside down (any X, Y, Z orientation).

Maxtor wrote:

The hard drive can be mounted in any orientation.

Samsung wrote:

As long as it is securely attached to the chassis, hard disk drives may be mounted either horizontally or vertically depending on how your computer's case is constructed.

While my hypothesis is that any of the devices will work fine at these orientations, and they are merely attempting to limit liability, since they all work using the EXACT same technology, it would seem that Seagate and Maxtor make the 'hardiest' harddrives.

Last edited by Splinter on Sat May 07, 2005 1:43 am, edited 2 times in total.

As I've seen this asked in about a dozen threads over the last week, I thought I'd clear this up.

Any harddrive made in at least the last 5 years can be mounted at any angle.

Upside down, on their side, on one end, at 45 degrees, balanced on one corner, whatever you like. You can even change the orientation without reformatting.

All that's important is that you avoid moving the hard drive while it's in motion, and you mount it in a secure fashion, so it won't fall or get banged against the side of the case while in operation. Also, make sure it's mounted in such a way that it won't over heat. Checking the SMART temperatures for a few days after mounting it with a program such as Speedfan is a good practice.

I do know for a fact this is true, as I've had harddrives operating in any angle imaginable for months on end, and it's just common sense. The heads of the HD operate under extreme accelerations, many tens of Gs. One extra G in any direction will be completely unnoticed. Heads aren't programmed with the physical locations of tracks and sectors, they find them intelligently.

6.7.4 Drive mountingThe drive will operate in all axes (6 directions). Performance and error rate will stay within specification limits if the drive is operated in the other orientations from which it was formatted.

Western Digital wrote:

Physical mounting of the drive:WD drives will function normally whether they are mounted sideways or upside down (any X, Y, Z orientation).

Maxtor wrote:

The hard drive can be mounted in any orientation.

Samsung wrote:

As long as it is securely attached to the chassis, hard disk drives may be mounted either horizontally or vertically depending on how your computer's case is constructed.

The quotes proves the opposite true.

Hitachi wrote:

6.7.4 Drive mountingThe drive will operate in all axes (6 directions). Performance and error rate will stay within specification limits if the drive is operated in the other orientations from which it was formatted.

"6 directions", we know what that means as it has 6 sides.

Western Digital wrote:

Physical mounting of the drive:WD drives will function normally whether they are mounted sideways or upside down (any X, Y, Z orientation).

"Sideways or upside down", not a combination of two or three axes. Otherwise there would not be commas between the XYZ letters.

Maxtor wrote:

The hard drive can be mounted in any orientation.

"any orientation", the word orientation is relative to the environment. As computers are built with cubic architecture they probably mean the same thing as the others. I can't tell more by that quote.

Samsung wrote:

As long as it is securely attached to the chassis, hard disk drives may be mounted either horizontally or vertically depending on how your computer's case is constructed.

"horizontally or vertically depending on how your computer's case is constructed."

It should be mounted perpendicular, you misinterpreted the information.

HP has sold thousands of PC's in the UK, most cases are cubic, but HP decided to attach lots of ugly plastic to the front, and had "Tilted" the front of the cases up by about 2 inches, therefore the FDD, HDD, and optical drives all operated at odd angles.!!!

I dont know what the faliure rate is/was, but I can tell you there were LOTS of problems with the Optical drives.

As far as hard drive mounting goes, I would only ever suggest as Tibors stated, any right angle to gravity.

Also bear in mind, no manufacturer is going to give anything away, they are not going to say only mount it one way, as that will hurt sales.

One other question to throw into the melee. What about suspension, direct case screwing, and rubber gromments etc.

To my knowlege, no manufacturers actually suggest anything other than screwing drives directly to cases, no grommets, or suspension.!!!

Well if having drives at odd angles damages them, what on earth is suspension doing to them. I have never suspended a HDD, but I am tempted to.

Presumably the drives still, rattle, and vibrate, and probably even wobble as well, but the noise is NOT transfered to the case, but by NOT stopping the drives from the above, will they get damaged.???

How are the drives of owners of SFF systems that are tilted (like the recent review of the AOpen EY855-II) holding up? Like the HPs mentioned earlier by AndyB, many shuttle SFF cases are tilted up in the front and the drive cage is oriented so that it tilts with it. Have drives proven reliable in such cases?

Alternatively, if the drive cage in a tilted case were mounted to orient the drives vertically and aligned axially front-back, the spindle would still be at a right angle to gravity. Any shuttle cases like that? Or is it a common mod?

The one regarding the 6 axes merely states that they will definately work at any right angle to gravity, something that is STILL contested on this board. It doesnt say they will not funciton properly at other directions.

The maxtor quote says 'any orientation'. It does not say right angles to gravity, it does not say parrell with the sides of the case, it says any orientation.

After 6 months of running a Maxtor DM9 at about a 30 degree vertical angle, as my primary drive in a computer which was always on and almost constant HD activity due to downloads and folding, there were no changes in drive mechanics tests or SMART readings. The same drive is now being used in my computer horizontally simply because it fits in the case better this way.

Both manufacturor whitepapers and personal experience show that in modern hard drives, any 90' angle to gravity is without a doubt completely safe, and any other angle is almost certainly fine, and any problems it does cause are so small that they are easily made insignificant by the multitude of other problems that crop up in drives for entirely different reasons

The one regarding the 6 axes merely states that they will definately work at any right angle to gravity, something that is STILL contested on this board. It doesnt say they will not funciton properly at other directions.

The maxtor quote says 'any orientation'. It does not say right angles to gravity, it does not say parrell with the sides of the case, it says any orientation.

After 6 months of running a Maxtor DM9 at about a 30 degree vertical angle, as my primary drive in a computer which was always on and almost constant HD activity due to downloads and folding, there were no changes in drive mechanics tests or SMART readings. The same drive is now being used in my computer horizontally simply because it fits in the case better this way.

Both manufacturor whitepapers and personal experience show that in modern hard drives, any 90' angle to gravity is without a doubt completely safe, and any other angle is almost certainly fine, and any problems it does cause are so small that they are easily made insignificant by the multitude of other problems that crop up in drives for entirely different reasons

Maybe they don't prove the opposite true, but you're doing much worse. At least my post can not cause anyone data loss, maybe yours won't either, but maybe is not good enough in this case. Bad things can happen by jumping to conclusions.

None of the quotes are specific enough to declare that 'any other angle is almost certainly fine', it would hardly be assuring anyway.
PC is about standards and most likely 'any orientation' is bound to different case design standards. The product is made to be used with standard parts, they don't care for homemade experiments.

If by 'about a 30 degree vertical angle' you mean that the drive is vertically perpendicular meaning the disc axis is perpendicular then I don't see any problem with it.

Bearings probably handle extra torque of angle mounting but maybe not head arms in operation. Gyroscopic force and gravity might displace the disc axis so that pressure against the heads change. Altered head arm pressure and gravitational downforce by the angle might in operation cause head crashes.
I'm no physicist but I think the example of 45 degrees in your first post would be the worst, being the angle furthest away from perpendicular.
As a matter of fact hard drives will fail when operating at too high altitudes because the air pressure is too low.

To sum up:
As long as the drive is perpendicular to gravity it's undoubtedly within specifications.
As long as the disc axis is perpendicular to gravity it's most likely within specifications.
Small angles must be accounted for (probably the tilted cases mentioned remain within specs).

HDs crash at low air pressure because they rely on the spinning action of the drive to create a cushion of air on which the heads will be suspended. Thsi will not be affected by any angle, it is purely an aerodynamic effect.

The only possible reason that a tilted drive would have trouble would be uneven wearing of the bearings, but that is a non-issue with FDB.

If the heads work vertically, and they work horizontall, they will work at any angle in between. I'll admit I havent gotten into complex aerodynamics, but I've done basic university physics, and combined with plain old common sense, there is absolutely no reason why the hard drive would fail as a result of being put at an angle.

The HD I had running at 30' was on an angle like this (looking at the connectors on the back of the drive): /

30' away from vertical, the bearings and heads definately working at an angle.

Not to make this thread any more pedantic than it already is, but if one is going to insist that their drives run horizontally, right-side up, I hope they're prudent enough to also own an online UPS and had a Faraday cage set in the walls of their bunker when it was built.

It's not 'purely an aerodynamic affect', it's also mechanical tension, maybe this explains my theory better:
I'll call the axis the head moves along the disc surface X, and the axis of the spindle Y.

When the head is fetching bits of data scattered on the disc it flies extremely fast to the left and right (X axis) over the disc stopping and changing direction with strong g-forces. The arm is built for max performance and so has minimal mass required to withstand the g-forces along the X axis. The X axis of the arm is wide but built like a triangle with holes in it to reduce mass. The Y axis of the arm is thin to reduce mass further and the spring steel is also what makes the head maintain proper pressure (flying height) against the disc. That means the Y axis of the arm has to bend somewhat, if the head is above the disc when stationary it will be pressed against it.

Let's say the disc axis is 45 degrees in operation and the head is flying 'downhill', when the head arm stops it's inertia and gravity continues to pull it downwards. The arm then springs back upwards and is also bounced away from the disc by the extra compressed air cushion. This 'trampoline effect' can be boosted by several following accelerations and decelerations and might finally throw the arm off balance enough to crash the head into the disc.
The arm might not be built to handle the extra downforce introduced to the Y axis by the angle. So what worries me is the delicate Y axis construction of the arm combined with the gyroscopic force worsening the situation by tilting the disc axis. The flying height of the head is a fine balance act to begin with, the extra forces might screw it up.

By the way, I don't know about notebook drives, but being much smaller they may not be affected as much, if anything at all. They are built in mind that they might even be moved somewhat in operation.

Your second paragraph makes sense but your third doesn't. When mounting a drive at an arbitrary angle, what changes the forces on the heads/arms in the direction of the axis of the spindle?

Think of a drive in the horizontal orientation. The arm above the disc has a worst-case effect of gravity pulling the arm towards the disc, and the arm below the disc has a worst-case effect of gravity pulling the arm away from the disc. Now flip the disc over, and these cases are reversed but worst-case in the other direction.

Think of a disc standing up on edge. Now when the arms move towards the centre of the earth their acceleration/deceleration is assisted/countered by gravity. But gravity now does not pull the arms towards/away from the platters.

In both of these cases above the arms have a small mass so the effect of gravity can't be very much compared to the g forces the arms experience in their own quick movement. In the horizontal case gravity is the only force I can think of in the direction of the axis of the spindle. In the vertical case there's nothing changing the forces on the arms in the direction of the axis of the spindle, unless you're moving the drive while it's in operation.

When the drive is mounted at an arbitrary angle between horizontal and vertical the effect of gravity on the arm in the direction of the axis of the spindle is somewhere between maximum (when the drive is horizontal) and the minimum (zero, when the drive is vertical), due to the shortened horizontal (wrt the earth's surface) dimensional component of the arm. If the drive is "okay" when both horizontal and vertical then why wouldn't the forces on the arms be okay when the drive is between horizontal and vertical?

Does the platter speed change when the arm is over different tracks, to keep the linear speed under the head constant (maximum)? The speed of the platters (and the air spinning in the drive) probably has an effect on the firmness of the air cushion that is greater than the effect of gravity on the small mass of the arms. You'd have to do some math to figure out the amount of change of the rotational speed, with respect to the diameter of the tracks, to keep the linear speed under the head constant.

I'd expect the bearings to have an easier time when the drive is horizontal but the drive manufacturers know their bearings best.

But what do I know, this is all guesswork. My own drives are suspended in a more-or-less horizontal orientation but I don't fuss about whether or not the drives are perfectly orthogonal wrt the surface of the earth.

Kevin

Edit: Sure the platter speed probably changes to keep the linear speed under the heads constant, but if the linear speed under the heads is constant maybe the firmness of the air cushion between the platter and head is also constant. (Assuming the air speed changes the same as the platter speed.)

Think of a drive in the horizontal orientation. The arm above the disc has a worst-case effect of gravity pulling the arm towards the disc, and the arm below the disc has a worst-case effect of gravity pulling the arm away from the disc.

Wouldn't that mean that only vertical mounting is optimal? I wonder what orientation is used when testing to determine MTBF figures. I doubt it would be possible to just ask manufacturers and get an honest answer.

I think there are some ads for fans somewhere that claim that because the 120 mm fan is horizontal, there isn't some other kind of wear on the bearings, which makes the bearings last longer. But fan bearings may be different than the bearings in drives.

Re what I wrote above, I guess if the drive were mounted at an arbitrary angle, the horizontal component of the arm's length would change as the arm moved back and forth, but, there is no "momentum" for length and the change in force, and the absolute force, applied to the arm in the axis of the spindle would not exceed the worst case that is (that I'm guessing is) present when the drive is horizontal.

Didnt notice that on the Hitachi, but stepping into the bounds of conjecture, such as everyone on the con side of this argument, I believe the reason they claim this is taht no cases are designed with HD cages on an angle.

They say use all four screws, therefore, if you mounted the HD using all four screw in a regular case and it was on an angle, you'd be doing something massievly wrong.

We here at SPCR all are well aware of the fact that HDs can be mounted with 0 screws quite safely.

Also, that is an instruction manual, not a technical white paper. Instruction manuals are designed partly by the legal department so as to minimize warranty claims. If some yahoo mounts his drive at an angle in such a way that the drive falls over and crashes the head, they dont want him saying 'well you never said I had to secure the drive'

Didnt notice that on the Hitachi, but stepping into the bounds of conjecture, such as everyone on the con side of this argument, I believe the reason they claim this is taht no cases are designed with HD cages on an angle.

They say use all four screws, therefore, if you mounted the HD using all four screw in a regular case and it was on an angle, you'd be doing something massievly wrong.

The part about using all 4 screws and securely mounting the drive has nothing to do with whether it is mounted at an angle. They want you to mount it securely with 4 screws even if it is mounted in a level horizontal position. Check out the link provided above to the Hitachi website.

If the drive was mounted at an angle, it could not be using all four screws.

They want you to use all four screws, therefore they do not want you to mount it at an angle.

No, I think you are wrong in your interpretation. They want the drive securely mounted with all four screws because "a loose drive may vibrate when in use and result in drive failure," regardless of what the mounting angle is. They are, in effect, recommending against suspending a drive.

I don't have enough knowledge of disk drive engineering to know how important that really is, but I do know enough about the English language to know what Hitachi is claiming.

No, I think you are wrong in your interpretation. They want the drive securely mounted with all four screws because "a loose drive may vibrate when in use and result in drive failure," regardless of what the mounting angle is. They are, in effect, recommending against suspending a drive.

I don't have enough knowledge of disk drive engineering to know how important that really is, but I do know enough about the English language to know what Hitachi is claiming.

I agree with your interpretation, but heres an interesting story . In a previous life, I worked briefly with a maxtor engineer and used some HD tools he wrote. We never cared much if the drives were fixed to anything when running stress tests. The drives were placed on a static bag on a flat surface (not too many angled surfaces in a lab). Anyway if I were to guess, neither flat nor suspended is particularly good for a drive, but from my limited knowledge I cant understand how it is particularly bad either. FWIW I have run drives non vertically for about 6 months of light use and upside down for a year of constant use. Sitting on foam pads for at least 2 years. No problems yet (well this seagate has always had some SMART errors but it works fine regardless). Take what you will from this anedoctal story

I suspect that it depends on how much vibration there is. If the drive vibrates a lot, the manufacturer would probably prefer that it be monted more securely. I think that it is somewhat accepted that it is not good for a drive to be operated while it is moving.

The head is mounted rigidly, and only moves in one direction. Gravity air cushion blah blah doesnt matter. Have a nice day.

Er, in operation the air cushion does matter, but I know what you mean heh.Anyways, the heads aren't mounted rigidly, unless you're just talking about the assembly as a whole mounted on the spindle they rotate on. At rest and while spinning up/down, the sliders of most drive heads are in contact with the platters. If you took the platters (or the heads) out without securing the heads properly, the top and bottom heads of each pair will collide with each other, they're basically spring-loaded. They're only supposed to move in one axis while the platters are spinning, it's more like a dynamic equilibrium.

kevinc wrote:

When the drive is mounted at an arbitrary angle between horizontal and vertical the effect of gravity on the arm in the direction of the axis of the spindle is somewhere between maximum (when the drive is horizontal) and the minimum (zero, when the drive is vertical), due to the shortened horizontal (wrt the earth's surface) dimensional component of the arm. If the drive is "okay" when both horizontal and vertical then why wouldn't the forces on the arms be okay when the drive is between horizontal and vertical?

Because, in this case, the heads are moving along two axes at once. Kind of an interesting thought actually, but I'm not sure that it'd make any difference whatsoever, since for the movement to affect the y position of the heads like that, the arms would sort of have to bend at an angle along their length. Even if this were within the realm of sanity, I think most drives would be inherently protected by it when tilted on one axis, by the nature of the heads only seeking from, say, 30 degrees to 50 degrees (just guessing), where the front center of the drive case = 0 degrees. If this is still making sense to anyone at all, you could then maximize the effect by rotating the drive 40 degrees to your left, then tilting it at 45 degrees vertically wrt your front and back (not the drive's), and doing a bunch of full-stroke seeks. And just in case I sound like a quack, I don't think this should happen at all because of the above, and more importantly because the arms are still being rotated parallel to the platters (well duh) in any case, and the fly height is still maintained by things totally independent of gravity.

...I worked briefly with a maxtor engineer and used some HD tools he wrote. We never cared much if the drives were fixed to anything when running stress tests. The drives were placed on a static bag on a flat surface (not too many angled surfaces in a lab)....

Not to go OT, but do Maxtor engineers normally make a habit of putting electronic components on the outside of antistatic bags (unless he turned them inside out first)... ?

If so, I wouldn't necessarily put too much faith in their judgement...

The benches are grounded anyway, so its just to separate the drive electronics from the metal. Some longer term tests were done with drives mounted, but a day or two stress test was just done quick n dirty.

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